Lubricating system for an internal combustion engine



.March 15, 1960 F. K. H. NALLINGER LUBRICATING SYSTEM FOR AN yINTERNAL. COMBUSTION ENGINE Filed March 26, 1956 ay 0m Ana/PIV .oi thefbodyof porousmaterial.

LUBRICATING SYSTEM-CRAN INTERNAL `COMBUSTION ENGINE Friedrich K. H. Nallinger, Stuttgart, Germanyyassignor to "Daimler-Benz Aktiengeselischatt, Stuttgart-Untenturkheim, Germany v.Application March 26, .1956, .Serial N o. 573,802

*11Claims. --"(Cl.'1`846) My invention relates Vto 'the lubricatingL system for an internal combustion engine and, more'particularly, to a system comprising a lubricant=dispensing conduit, 'a lubrieating pump driven'by theengine, and a filter interposed therebetween forthetpurposeof continuously cleaning the lubricant.

A preferred type of lters used insuch1systerns is .the so-called microiilter lconsisting of `a 'body of'porous material through which the 4lubricant Iis pressed. After a continued 'period offjoperation,hcwevergsuch `lteriis liable to be clogge'd'bythe impurities accumulated .therein and, Yas a` result, 'offersaihiglrresistance to the passageof the .lubricant and "may 'eventually prevent .the Ypassage thereof-altogether. lorthis reason,E iti isv the generalvpractice to'provide a.relief"valvebypassing the lter, such reiieivalve bein'g'a'djusted to open in responseto an excessive `'pressure 'ofthe lubricantithus permittingthe latter'tobezsuppliedto thelubricating-points ofthe engine even lthough 's ch lubricantwillihe cleaned nolonger.

v fheprior lubricating systems comprising ,a microflter and `a relier valvebypassing lthesame may 'fail under certain conditions or"v '.operation, however. When the engine is idlingor is operating aha low speed, the lubricating pump drivenby'the engine may not., be .able to produce a suflicient. pressure to open the relief .valve or to overcome the resistance of the lter. As a result, the hibricatingk points of the engine WilLnotbe supplied with lubricant. "lhisfaultyconditionof operation isparticularlyliableto'happen where'thepump'has a'high leakage duetowear and where the lubricant is'highlyheated and, therefore, has alow viscosity. y. M

. tis the 'objectof thejpresentinvention to provide an `improved'lubricating system in which vthe afore-described yshertcomings oftheprior lubricatingsysterns are avoided. More particularly, it isan object of my inventiontonprovide an improvedlubricating systern'inclu'ding a iilter and a relief valve bypassing 'the same which ensures a supply .oiilubricantlto the engine even whenthe same isidling a micrclterformed by abody of ,porous material `and o a..screen,such filter beingof compact structure lending itself to manufacture at low costs and beingreliablein operation and .permitting easy.A disassembly .l and :exchange 'further objects of my invention will .fappear 'from-e Vdetailedxdescription of :afnurnber fof preferred .embodi- .ments of the invention'foll'ovvinghereinafter vWithfreferencetothe drawings, it being understood that the terms :and phrases .useddn such-detailed Vdescription have been. 'cvliosenforthe purpose of 'illustration ratherv thanV that of restriction or, limitation of the invention. Thefeatures r Y 4EC@ iImthe-drawings, ".Fig. 1 illustrates 'an internal `conibustionlengine provided with thenovelllubricating system,-"thelatterbeing shown'more or less diagrammatically,

Fig. 2is an axial section taken through-arelieffvlve p modication of theiilter housing shown therein.

The internal 'combustion engine 9 shoWn-inFig. -`1-is geared toa'lubricating pump 1li to drive the'sameand is equipped'with a lubricant-dispensing conduit'l having a plurality-of 'discharge4 ports 14 leading'to the-lubricating y the"pump,'when feeding the lubricant during low speed Y ofthe-engine at alow pressureinsuiiicient to 4ope'rrthe Vrelief -valve 'l7'against the'pressure of the spring *.16 or to overcome the resistance of the-filter 12, tojsupply the conduit '13 withthelubricant. Shouldit happen after operation of the v-engine overa 'continued period Vof "time that'the'resistance of the tilterz hasunduly increased .bythe accumulation-of foreigni'matter therein, `and should lthe `pump it) Yproduce insufcient pressure to .open the Vrelief valve, the,lubricant'supplied,through'the restricted passageway 19 will still ybesumcient to ensurelubrication 'of theengine and, more particularly,-ofrthe crankshaft bearings-supplied bythel discharge ports .14 ofthe conduit i3. The throttling'effectof the restrictedkpassageway19 is so chosen that the quantity Yof oil supplied through the'passageway '19 will sniiice for the idling operationof the engine, but isl so limited that during operationof the engine under load ionlya negligible portion of the entire. v quantity of' lubricant circulated throughthe engine flows Y through the passageway, Whereasthe major portion of the'oil istorcedto pass'thetllter 12 to becleaned therein. Thus, kthelter i2 will be interposedin the main "branch `of the stream `0i" lubricant when .the engine is 'operatingunder load, and Vduring the idling of theV engine orduring'the operation atextremely low speeds only will the [filter beineiective. vPreferably, the relief valve is Acomposed of a housing member, such as "22shownin 2, of a ball, such asll, seated thereon, vand lof a spring, Suchas 2i), coordinated tothe ball 21 and tending `to press the same upon the'seat. in ,a relief valve of this type, the restrictedrpassageway may be formed by a groove, such as 23,' provided inthe seat ofthe valve. "If

desiredfa pair of such grooves'23 may beprovidedy as Y shown in Figs. l and 3. The oil entering the housing 22 through the inlet port 24'may pass through the-slots 23 to the outlet port ,25 even should the pressure of the lubricant be insuicientto lift the ball 21 from the valveY having a valve stem provided with the longitudinal ib'ore' 26 a valvehead 28 cooperating with the valvewseat. The .bore `26 constitutes a ,restricted passageway permanently connectmg the inlet port 24 of the valve hous-v 33 and an outlet 34. VThe cover 32 provides a stepped seat for a member S constituting a means formounting filter 30 to space 42 referred to in the claims as the third space and from there to the outlet 34.

Preferably, the loading springs 44 and 46 are adjustable and, for this reason, abut against threaded plugs 54. Should it happen after continued operation of the engine over a long period of time that both the coarse filter 29 and the fine filtere30 will be obstructedby the accumua `cQarse filter29and a fineV filter ormicrofilter-30 within i, i

n remain sufficiently unobstructed 'to permit the lubricant to the housing with a space 38 between such filters so as to establish a lubricant 'circuit from the inlet 33 through the coarse filter 29, the space 38 and the line filter`30 to the outlet 34. The coarse filter 29 is formed by a sheet metal cylinder provided with a multiplicity of circumferential slots supported Von its inside by a perforated cylindrical sheet metal member 37. The microfilter 30 is formed by a substantially cylindrical hollow body of a porous material surrounded by the perforated sheet metal` the member VASli being'fixedrthereto by a nut 53. Pref.-

erably,\thes'tem 52 is'hollow for the accommodation of a bolt 35 screw-threaded therein and having its upper end in threaded engagement with a nipple inserted in a bore of the cover 32 and being seated thereon. Duringrnormal operation the lubricant circulates through Vthe housing along the path indicated by the arrows extending from the inlet 33 downwardly into the peripheral space sur rounding the coarse filter 29, then through the latte'i` to the space `38 between the two filters, and thence through the fine filter 30. In the interior space of the fine filter accommodating the bolt 52 the lubricant passes upwardly and flows through bores of the member 50 into a central bore of the cover 32 and thence through the outlet 34 communicating with such central bore.

For the purpose of the present invention, the cover 32 is provided with a first duct connecting the inlet 33 with the outlet 34, a first reliefvalve having a spring 44 being providedrin said first duct. Moreover, theV filter housing is provided with a second duct 39 extending through the mounting member and communicating with an annular space 41 from which the duct further extends through the cover 32 into the outlet 34. In this duct there is inserted a second relief valve 47 provided with a spring 46.

For the purpose of the present invention, a restricted passageway 48 is provided in the cover 32, such passage- Y way bypassing the first relief valve 45. As shown in Fig. 6, means for adjustingthe throttlingeiect of the The filter housing described offers the advantage of easy disassembly. Upon unscrewing the nipple 36 the cover32 may be readily removed from the housing `31 lation therein of foreign, matter, the lubricant may flow directly from theV inlet 33 to the outlet V34 through the restricted bore 48'i f the pressure ofthe lubricant should n be insufiicientrto lift therelief valve 45. Upon increase of the pressure, however, the lubricant may, pass 'the relief valve 45. As long,'howcver, as the coarse filter29 will` pass, such lubricant may flow, through the restricted passageway 48 or, ifits pressure is sufficient, through the check valve 47 to the outlet 34 if the fine filter 30 should be obstructed, The fine filter 30 is provided with an end plate abuttingagainst a sealingring 5,5 which is inserted in the bottom face of the mounting member 50 and serves to separate the outer space 38 from thecavity 42 communicating with the internal space of the fine filter 30. If desired, the passageway 48 may be disposed adjacent to the valve 45.

From the'foregoing it Vwill `appearthat my invention` avoids the disadvantage of the prior lubricating systems. The restricted passageway bypassing the filter' has such a.

crossv section that under normal conditions of operation;

at a high. speed theniajorityof thelubricant `willflow through the filter, and that at an operation at a low speed or withl a high resistanceof the filter the majority of the lubricant will pass through the restricted passageway.

While 'the invention has been describedy in connection with a number of preferred embodiments thereof, it will be understood that it is capable of furthermodification, and this application ofthe invention following, in general,-t,h e principles of theinvention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, andas fall within the scope of the invention or the limits of the appended claims.

'1, Lubricating system for an internal, combustion engine comprising a lubricating pump driven by the engine, a lubricant-'dispensing conduit, a filter having an inlet` and -an.outlet, `said inlet communicating with said pump and saidoutlet communicating with said conduit,

and a relief valve having an inlet and an outlet, the inlet` of said .relief valvepermanently communicating with the t inl'et of saidfilter,and thefoutlet of said relief valve permanently Acornmi'inicating with the outlet'of said filter, said relief valve byfpassing said filter, a restricted passage-wayjcoordinated to at least one of the aforementioned elements; of the combination for establishing a direct permanentcommu'nication between at least one of said inletsand at leastV one of said outlets to afford said pumplja'possibility of supplying 'saidcondnit `with lubricant, when feeding the lubricant during low speed of said engine at a low pressure which is insufficient to open said relief valve and insufficient to overcome the resistance of said filter.

2. System4 as claimed in claim 1 further comprising means for adjusting the throttling eEect of said'restricted passageway. A

3. System as Vclaimed `inclainti 1 further comprising a 1 needle valve for adjusting the cross section of said re and then permits ready access to the filters for exchange.

thereof.

In operation the lubricant normally flows from the stricted passageway. n

A 4. Systemv as claimed in V.clairn 1 in which said relief valve isycomposed ofa` housing member having aseat, of a ball seated thereon, and of a spring coordinated to said balland tending to press the same uponsaid seat, said restricted passageway being formed by a groove in said seat. ,n l t 5. System as claimed in claim 1 in which a common housing is provided p for said filter and for said relie! valve, said restricted passageway being provided within said housing. Y

6. A filter for the lubricant system of an internal combustion engine comprising a housing provided with an inlet and an outlet, a coarse filter, a fine filter, means for mounting said filters in said housing with a space between said filters and for conducting a stream of lubricant from said inlet through said coarse filter, said space and said fine filter to said outlet, a first duct connecting said inlet with said outlet, a first relief valve in said duct, a second duct connecting said space with said outlet, a second relief valve in said second duct, said means being provided with a restricted passageway bypassing said first relief valve.

7. Filter as claimed in claim 6 in which said means are provided with a second restricted passageway bypassing said second relief valve.

8. A filter for the lubricant system of an internal combustion engine comprising a cup-shaped housing, a cover, means for releasably securing said cover in posivtion on said housing, a stem coaxially disposed in said housing, an annular member fixed to saidstem in spaced relationship to the bottom of said housing and in engagement with said cover, a cylindrical screen in said housing in coaxial relationship to said stem extending between said annular member and the bottom of said housing being spaced from the side wall of the latter to confine a first space therewith, a micro-filter formed by a substantially cylindrical body of porous material having an axial bore and being mounted within said screen in spaced relationship therefrom to confine a second space therewith and extending between said annular member and the bottom of said housing, said stern extending through said bore, said member being provided with a cavity which communicates with said bore and` constitutes a third space, said cover'being provided with a lubricant inlet port communicating with said first space, with a lubricant discharge port and with a conduit establishing a direct communication between said lubricant discharge port and said third space to be supplied with lubricant that has flown inwardly through said screen and through said micro-filter, a first spring-controlled relief valve having an inlet and an outlet and mounted in said cover, said inlet permanently communieating with said inlet port and said outlet permanently communicating with said discharge port, a first restricted passage-way being provided in said cover leading from said inlet to said outlet, communicatingducts being provided in said cover and in said annular member to constitute a direct communication between said second and said discharge conduit, a second relief valve mounted in one of said communicating ducts to afford flow of lubricant from said second space to said discharge conduit under pressure, and a second restricted passage-way provided in said cover leading from said second space to said discharge conduit for by-passing said second relief valve. p

9. Lubricating system for an internal combustion engine having elements to be lubricated, said system comprising a lubricating pump driven by the engine and provided with an outlet, conducting means connected to said pump and to said elements for conducting a stream of lubricant from said outlet to'said elements, a filter screen co-ordinated to said conducting means and arranged across said stream for filtering samein a coarse manner, a micro-filter ofporous material co-ordinated to said conducting means and arranged downstream of same in a fine manner, and a relief valve having an inlet and an outlet and co-orcrlinated to said conducting means so that said inlet permanently communicates with Y a restricted passage-way leading from said inlet to said said filter screen to extend across said stream for filtering Y outlet establishing a direct permanent communication therebetween to afford the pump a possibility of supplying'said elementsY with lubricant, when feeding the lubricant during low speed of said engine at a low pressure which is insuflicient to open said relief valve and insufficient to overcome the resistance of said filters.

10. Lubricating system for an internal combustion engine having elements to be lubricated, said system comprising a lubricating pump driven by the engine and provided with an outlet, conducting means connected to said pump and to said elements for conducting a stream of lubricant from said outlet to said elements, a filter screen co-ordinated to said conducting means and arranged across said stream for filtering same in a coarse manner, a micro-filter of porous material co-ordinated to said conducting means and arranged downstream of said filter screen to extend across said stream for filtering same in a fine manner, and a relief valve having an inlet and an outlet and co-ordinated to said conducting means so that said inlet permanently communicates with said stream at a point located downstream of said filter screen and upstream of said micro-filter and that said outlet permanently communicates with said stream at a point located downstream of said micro-filter, said conducting means being provided with a restricted passageway leading from said linet to said outlet establishing a direct permanent communication therebetween to afford the pump a possibility of supplying said elements with lubricant, when feeding the lubricant during low speed of said engine at a low pressure which is insufficient to open said relief valve and insufficient to overcome the resistance of said micro-filter.

11. System as claimed in claim l0 further a second relief valve having an inlet and angoutlet and co-ordinated to said conducting means so that rthe inlet of said second relief valve permanently communicates with said stream at a point located Vupstream of said filter screen and that the outlet of said second relief valve permanently communicates with said stream at a point located downstream of said microfilter, said conducting means being provided with a second restricted passage-way leading from the inlet of said second relief valve to at least one of said outlets establishing a direct permanent ycommunication therebetween to afford the pump a possibility of supplying said elements with lubricant, when feeding the lubricant during low speed'of said engine at a low pressure which is insufficient to open said relief valve and insufficient to overcome the resistance of said filter screen, if the latter should get clogged.

References Cited inthe file of this patent Y UNITED STATES PATENTS 1,656,200 Horning Jan. V17, 1928 1,857,651 McKinley May 10, 1932 2,602,547 Floss July 8, 1952 FOREIGN PATENTS 293,745 Great Britain Apr. 25, 1929 709,897 Great Britain June ,2, 1954 comprising 

